genirq/msi, x86/vector: Prevent reservation mode for non maskable MSI

[sfrench/cifs-2.6.git] / kernel / irq / msi.c

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index edb987b2c58dc1553342b5a87c91335b42888e8b..2f3c4f5382cc6bad8daf528146cf613d9a1ac3e6 100644 (file)
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -339,6 +339,40 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
        return ret;
 }
 
+/*
+ * Carefully check whether the device can use reservation mode. If
+ * reservation mode is enabled then the early activation will assign a
+ * dummy vector to the device. If the PCI/MSI device does not support
+ * masking of the entry then this can result in spurious interrupts when
+ * the device driver is not absolutely careful. But even then a malfunction
+ * of the hardware could result in a spurious interrupt on the dummy vector
+ * and render the device unusable. If the entry can be masked then the core
+ * logic will prevent the spurious interrupt and reservation mode can be
+ * used. For now reservation mode is restricted to PCI/MSI.
+ */
+static bool msi_check_reservation_mode(struct irq_domain *domain,
+                                      struct msi_domain_info *info,
+                                      struct device *dev)
+{
+       struct msi_desc *desc;
+
+       if (domain->bus_token != DOMAIN_BUS_PCI_MSI)
+               return false;
+
+       if (!(info->flags & MSI_FLAG_MUST_REACTIVATE))
+               return false;
+
+       if (IS_ENABLED(CONFIG_PCI_MSI) && pci_msi_ignore_mask)
+               return false;
+
+       /*
+        * Checking the first MSI descriptor is sufficient. MSIX supports
+        * masking and MSI does so when the maskbit is set.
+        */
+       desc = first_msi_entry(dev);
+       return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
+}
+
 /**
  * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
  * @domain:    The domain to allocate from
@@ -353,9 +387,11 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
 {
        struct msi_domain_info *info = domain->host_data;
        struct msi_domain_ops *ops = info->ops;
-       msi_alloc_info_t arg;
+       struct irq_data *irq_data;
        struct msi_desc *desc;
+       msi_alloc_info_t arg;
        int i, ret, virq;
+       bool can_reserve;
 
        ret = msi_domain_prepare_irqs(domain, dev, nvec, &arg);
        if (ret)
@@ -385,6 +421,8 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
        if (ops->msi_finish)
                ops->msi_finish(&arg, 0);
 
+       can_reserve = msi_check_reservation_mode(domain, info, dev);
+
        for_each_msi_entry(desc, dev) {
                virq = desc->irq;
                if (desc->nvec_used == 1)
@@ -397,15 +435,25 @@ int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
                 * the MSI entries before the PCI layer enables MSI in the
                 * card. Otherwise the card latches a random msi message.
                 */
-               if (info->flags & MSI_FLAG_ACTIVATE_EARLY) {
-                       struct irq_data *irq_data;
+               if (!(info->flags & MSI_FLAG_ACTIVATE_EARLY))
+                       continue;
 
+               irq_data = irq_domain_get_irq_data(domain, desc->irq);
+               if (!can_reserve)
+                       irqd_clr_can_reserve(irq_data);
+               ret = irq_domain_activate_irq(irq_data, can_reserve);
+               if (ret)
+                       goto cleanup;
+       }
+
+       /*
+        * If these interrupts use reservation mode, clear the activated bit
+        * so request_irq() will assign the final vector.
+        */
+       if (can_reserve) {
+               for_each_msi_entry(desc, dev) {
                        irq_data = irq_domain_get_irq_data(domain, desc->irq);
-                       ret = irq_domain_activate_irq(irq_data, true);
-                       if (ret)
-                               goto cleanup;
-                       if (info->flags & MSI_FLAG_MUST_REACTIVATE)
-                               irqd_clr_activated(irq_data);
+                       irqd_clr_activated(irq_data);
                }
        }
        return 0;